The invention relates to a cooling system for cooling tool parts with the aid of a fluid guided from a fluid inlet through connector lines to a fluid outlet, the tool parts being connected in the direction of through-flow between at least one connector line connected to the fluid inlet and at least one connected to the fluid outlet.
EP-B2-0 283 644 discloses an injection moulding machine which has an injection moulding plate with cavities and a core plate with projecting cores, the number of cores corresponding to the number of cavities. As the moulding plate on the one hand and the core plate on the other move towards one another, the cores engage in the cavities and, in the closed position, form between them the injection mould cavity in which a hollow parison made of synthetic material is shaped by an injection moulding procedure. These parisons, which are in particular made of PET, are later used to make the known PET bottles by blow moulding (PET is polyethylene terephthalate). After the injection moulding, the parisons have to be cooled sufficiently so that they can be processed after the injection moulding procedure without damaging them.
The cooling is carried out in the known injection moulding machines on tubes which are secured to a carrier plate and through which a fluid, in practice cooling water, flows, hence cooling them.
So that it is possible to cool a large number of tool parts, for example tubes or cores, at the same time in as compact a machine as possible, carrier plates with a plurality of tubes secured thereto and with fluid lines running in the carrier plate have been developed. The cooling water is guided for the whole carrier plate, in parallel and more or less simultaneously, from the fluid inlet to the tubes, through which it flows as the relevant tool parts. After that the cooling water, which has been heated up to a certain extent, is guided out through a fluid outlet.
The known cooling system has the features mentioned at the outset, which are also reproduced in the precharacterising clause of the main Claim 1.
The known cooling system suffers from considerable disadvantages, however. Although the cooling lines in the individual tool parts, for example the cores, each have a small cross-section taken by themselves, with a large number of cores through which there is flow simultaneously the individual line cross-sections add up to a considerable size. If we take as an example a known fluid inlet having a diameter of 2.54 cm, then around 2000 mm2 is available as the inlet surface area. The same applies to the fluid outlet. In the case of a 48x core plate, on the other hand, the corresponding cross-sections through which there is flow provide a total surface area of 3770 mm2. This large surface area of consumption is provided with only the small above-mentioned cross-sectional surface area at the fluid inlet. The surface area to be provided to the cores is thus approximately twice the incoming surface area available for the cooling fluid. This means that there is a sharp fall-off in pressure from the fluid inlet to the outlet, and in the region of the cores there is hardly any turbulence because of the consequently lower flow rates of the fluid. In the absence of turbulence, however, the cooling effect drops drastically as well. At the same time, if the core plate contains the connector lines it may disadvantageously clog up, because impurities settle and are not washed away, as a result of the slow flow and the low pressure in the fluid lines. The heat transfer between the fluid inlet and the fluid outlet is reduced, a further disadvantage.
For a cavity plate, the attempt has already been made to lessen these disadvantages and to increase fluid turbulence, by blocking the possibility of a fluid flowing through to a certain extent as a result of interruptions, in a construction used within the operation. This results in dividing into two a previously single line, and hence making two flow paths out of the originally single flow path. This earlier attempt at a solution relates to a mould plate of a specific shape, however, in which the cooling system is divided into complete sections by providing the interruptions, blocks or barriers in the individual connector lines.